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[RFC,03/22] KVM: x86: hyper-v: Honor HV_MSR_VP_RUNTIME_AVAILABLE privilege bit

Message ID 20210413122630.975617-4-vkuznets@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: hyper-v: Fine-grained access check to Hyper-V hypercalls and MSRs | expand

Commit Message

Vitaly Kuznetsov April 13, 2021, 12:26 p.m. UTC 
HV_X64_MSR_VP_RUNTIME is only available to guest when
HV_MSR_VP_RUNTIME_AVAILABLE bit is exposed.

Note, writing to HV_X64_MSR_VP_RUNTIME is only available from the host so
kvm_hv_set_msr() doesn't need an additional check.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/hyperv.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 781f9da9a418..b39445aabbc2 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1504,6 +1504,10 @@  static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
 		data = hv_vcpu->hv_vapic;
 		break;
 	case HV_X64_MSR_VP_RUNTIME:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_MSR_VP_RUNTIME_AVAILABLE)))
+			return 1;
+
 		data = current_task_runtime_100ns() + hv_vcpu->runtime_offset;
 		break;
 	case HV_X64_MSR_SCONTROL: